Week 12 - Project-1

Objectives:

1. To generate the middle surface as well as geometric clean-up of the car side door.
2. To generate a mesh and check the quality parameters of the elements.
3. To assign thickness together with properties for the component of the side door of the car.

CAD file:

Procedure:

Being a CAE Engineer, one has to categorize the given part into multiple components as the geometry is in complex shape.

Following is the procedure to classify the various components:

1. To split the surface as required:

This tool is mostly used to split the part into two different surfaces.

• Geometry – surface edit – with points.

Select the base point and axis to the normal.

1. To organize the surface in a different component.

As the surface needs to be assigned to a different component, we have to create a new component.

• Right-click – create – component.

For moving the surface to a new component follow the following procedure.

• Tools – organize – select surface – move.

1. To generate the middle surface of the component

As the component has a variable thickness, we have to generate a manual mid surface instead of an automatic generated surface.

As the thickness in 2.8, to generate middle surface offsetting one of the surfaces to 1.4 that is half of the thickness. This process is the same for all varying thicknesses.

1) To generate the middle surface of components.

As the model has a varying thickness it is difficult to extract the middle surface using an auto mid surfacing option. So, instead of using the auto mid surface, we have to manually duplicate the surface and offset it in the middle of the surface.

To offset the surface we have to check the thickness and then offsetting the surface to its half thickness.

1. Check the thickness of the surface

Geometry – Temp nodes – create

• Tools – Project – to surface – node – Duplicate

• F4 – Distance – Two nodes

Generate Middle surface by offsetting the surface:

Geometry – Surface Edit – Offset – distance 1.4 – Duplicate – Offset

Manually create a middle surface for the complete geometry

In some regions like ribs, it is not possible to generate mid surface using the offset option as the thickness varies with respect to length in such case we have to create the surface using the two lines.

1) Geometry – Line – Middle Line - create

This tool will generate a line in between two lines this line is used to generate surface by defining two lines.

2) To project line on surface:

Geometry – surface edit – trim using the line

3) Create surface using Two lines

Geometry – surface – two line – Create

This process of generating a middle surface is applicable to surfaces that do not have a uniform thickness.

2) To clean up the geometry and create a mesh.

Before cleaning the surface, we have to specify the editing parameters and at the same time, the “edit criteria”. While the editing parameter deals with geometry clean-up, the “edit criteria” deals with the element quality. Another important factor is that the element criteria are pre-determined within the problem statement.

The quality parameters are as follows.

As the above given geometry is of complex shape, we have to generate the so called “quad dominating mesh” since we are going to use a mixed type mesh character and at the same time, keep the element size as 4. Also, in order to capture the whole surface properly, we have to manually generate mesh over the same region. To generate a clean mesh flow, we have to smoothen the mesh. The next step is to eliminate the “TRIA” since we have to combine the opposite direction of the so called “TRIA” by dragging it on top of each other.

Some of the elements in this case also fail in quality since in such conditions, we can use the element optimization tool or alternatively, the element clean-up tool.

There are some ground rules to be taken into consideration:

1) Optimizing the use of “TRIA”.

2) Eliminating the rotational Quads.

3) Placing the TRIA in the middle of geometry i.e. to avoid the use of TRIA on the edges.

4) Do not place TRIA in the fillet region.

3) To check the Quality parameters of elements.

i) Tools – check Elements – parameters

Manual eliminating of the poor quality elements.

ii) Check the normal direction of the surface.

The direction of normal should be in a similar direction. Only then will the element will react similarly to the loading conditions.

Tools – Normal –Displayed

Make sure the elements are displaying a similar colour. If not, then manually reverse the direction of the normal direction.

iii) To check the dependency of element and penetration.

The element should not depend on more than 1 element. If it is more than 1, then the element will fail while solving the loading condition. The purpose of the penetration tool is to check whether elements are not overlapping with other elements or intersecting with each other.

iv) To associate the thickness to model

Right-click – Create – Properties - thickness – 2.8

If the thickness is different on various sections of the surface the create multiple properties of multiple thicknesses.

Components – properties – Properties

This process applies to all the components.

Conclusion:

With this exercise, we learned new tools that would improve the accuracy, quality, and at the same time, reduce the meshing time. We also learned new features such as Auto mesh, Quality Index, removing rotational Quad, eliminating “TRIA”, smoothing the element flow, changing the quality parameter, Auto clean-up and its parameters, importance of washer, and the projection of nodes.

Result:

From this project, we got to know the tools to generate a mesh and to clean-up the quality of elements. We also learned various techniques to generate mesh effectively.

Final component: